EP0001692B1 - Dispositif d'ajustage automatique pour une presse - Google Patents

Dispositif d'ajustage automatique pour une presse Download PDF

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Publication number
EP0001692B1
EP0001692B1 EP78300446A EP78300446A EP0001692B1 EP 0001692 B1 EP0001692 B1 EP 0001692B1 EP 78300446 A EP78300446 A EP 78300446A EP 78300446 A EP78300446 A EP 78300446A EP 0001692 B1 EP0001692 B1 EP 0001692B1
Authority
EP
European Patent Office
Prior art keywords
press
carrier
ram
platen
cylinder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP78300446A
Other languages
German (de)
English (en)
Other versions
EP0001692A1 (fr
Inventor
William Derek Robinson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Delta Materials Research Ltd
Original Assignee
Delta Materials Research Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Delta Materials Research Ltd filed Critical Delta Materials Research Ltd
Publication of EP0001692A1 publication Critical patent/EP0001692A1/fr
Application granted granted Critical
Publication of EP0001692B1 publication Critical patent/EP0001692B1/fr
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/28—Arrangements for preventing distortion of, or damage to, presses or parts thereof
    • B30B15/281—Arrangements for preventing distortion of, or damage to, presses or parts thereof overload limiting devices
    • B30B15/284—Arrangements for preventing distortion of, or damage to, presses or parts thereof overload limiting devices releasing fluid from a fluid chamber subjected to overload pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J13/00—Details of machines for forging, pressing, or hammering

Definitions

  • the present invention relates to presses and is more particularly concerned with a device for controlling the operation of a press to avoid overloading due to incorrect positioning of a mould or platen in relation to the stroke of the press.
  • the invention is more particularly concerned with a press having a press ram, a platen towards and away from which the ram reciprocates, and a workpiece carrier supported by the platen between the platen and the ram for adjustment in the direction of the stroke of the ram.
  • the press has a determined ram stroke length and the press is to be used with a mould or a former, for example in hot stamping, drawing and embossing operations
  • the press is a mechanical press with a crank drive for the ram
  • the press is badly set so that the press closes before the crank reaches its bottom dead centre position, the crankshaft becomes locked at the bottom of the ram stroke, if the press has insufficient power to complete the stroke; when that occurs, major maintenance is required to free the press.
  • One such device takes the form of tubes filled with ball bearings located behind the mould carrier; when press jamming occurs, the ball bearings are freed to run out of the tubes and allow downward displacement of the mould and so reduce the force on the crankshaft.
  • Another overload device takes the form of a mass of extrudable material, such as lead or a polymer, which is closely confined in a container having a small outlet.
  • the device is again located against the mould carrier and, when the press is improperly set, the resulting overload causes material to be extruded from the container to cause resetting of the mould in relation to the ram stroke and to remove the overload condition.
  • the disadvantage of the latter device is that it can be used only once and must be replaced by a similar device once extrusion has taken place.
  • An object of the present invention is to provide a device for a press that will automatically adjust the setting of the press when an overload occurs.
  • Another object is to protect a crank press from danger of crankshaft damage and to avoid the excessive noise which can be generated as a result of the press being badly set.
  • a press includes a reciprocable ram, a platen towards and away from which the ram reciprocates, and a workpiece carrier supported by the platen between the platen and the ram for adjustment in the direction of the stroke of the ram, characterised in that a self-adjusting device is operatively located between the platen and the carrier to determine the position of the latter relative to the former and to adjust that position in relation to the stroke of the ram, the device comprising: a fluid-container cylinder operatively connected to either the platen or the carrier; a cooperating piston movable in the cylinder and operatively connected to the carrier or platen respectively; a normally closed valve in the cylinder for discharge of some of the fluid when opened, the valve being arranged automatically to open when the pressure of the fluid exceeds a given value and to close after the pressure has fallen substantially to that value, so that the carrier is repositioned in relation to the platen and the ram stroke; and means to lock the carrier in its new position.
  • the valve In use, and where the workpiece carrier has been wrongly set so that an overload condition occurs at the end of the compressive stroke of the ram, the valve is automatically opened and sufficient fluid is released from the cylinder, firstly to cause the removal of the overload condition, and secondly to alter the setting of the workpiece carrier in relation to the ram stroke towards the correctly set position. After the carrier has been locked in position the press can then be operated with the carrier in its reset position.
  • valve opening means comprise a stiffly compressible plug located in the cylinder and separated from said piston by a volume of liquid, the port being normally closed by the plug but being exposed for discharge of some of the liquid when the plug is sufficiently compressed.
  • the combination of the valve port and the stiffly resilient plug form a cheap and reliable means for adjusting the carrier automatically. It has the further advantage that the self-adjusting device can be used repeatedly, without maintenance, apart possibly from topping up the fluid in the cylinder.
  • the press is of well known type having a press frame 10, a press bed plate or platen 12 and a fixed throw press ram 14.
  • the press ram 14 is reciprocated mechanically by a power- driven crank which can be for example of the key clutch type or the friction clutch type.
  • Such presses are so well known, further description of the mechanism for reciprocating the press ram 14 is unnecessary.
  • the fixed platen 12 carries a support plate 16 which supports a workpiece carrier 18, which can be adjusted in its separation from the platen 12 in order to set the press.
  • the carrier 18 in turn supports a mould or former 20 for performing a hot stamping, drawing or embossing operation.
  • the press ram 14 carries a press tool 22 which, when the press is properly set, closes on the mould 20 at the end of the compressive stroke of the ram 14 in order to perform the required shaping of the workpiece (not shown) within the mould 20.
  • each of the adjustable clamps 24 is bolted at one one to the platen 12 and, at the other end, overlies the carrier 18.
  • a self-adjusting setting device 28 is disposed between the plate 16 and the carrier 18, between which are also located a number, for example four, of stiff stabilising springs 30.
  • the self-adjusting setting device consists basically of a cylinder 32 and a cooperating piston 34 having piston rings 36 in sealing engagement with the bore of the cylinder 32.
  • a plug 38 is closely received in the end of the cylinder 32 and a volume of hydraulic liquid 40 is contained within the cylinder between the piston 34 and the plug 38.
  • a valve port 42 is formed in the cylinder wall at a level below the free face 44 of the plug 38, when the latter is undeformed.
  • the cylinder 32 is located in a cup 46 which catches any hydraulic liquid displaced from within the cylinder through port 42, as described later.
  • the plug 38 is stiffly resilient and for that purpose consists of a plug body 48 made of a suitable elastomer, such as a natural or synthetic rubber and preferably a silicone rubber.
  • the plug body 48 is surmounted by a steel retaining cap 50, which in turn carries a sealing cap 52 made of plastics material.
  • the cap 52 extends around the side of the plug and is in contact with the bore of the cylinder 32 over a substantial axial length. It seals the plug to the cylinder and prevents leakage of liquid 40 to and through the port 42, except when the port 42 is exposed on sufficient compression of the plug.
  • the device as shown in Figure 2 is secured in position as shown in Figure 1 by mounting the cup 46 in a recess 58 centrally in the plate 16 and the piston 34 in a recess 60 centrally in the underside of the carrier 18.
  • the device can be reversed, with the piston 34 secured in the plate 16 and the cylinder 32 secured in the underside of the platen 18.
  • the clamps 24 and the screw jacks 26 are either removed or slackened off to allow free movement of the carrier 18 relative to the platen 12; the carrier 18 is stabilised against cant by the springs 30.
  • the position of the carrier 18, and hence the mould 20 is then determined by the volume of liquid 40 within the cylinder 32 and that volume is so chosen that the press tool 22 closes on the mould 20 before the end of the compressive stroke of the. ram 14 is reached.
  • the press is then closed, preferably without a workpiece within the mould 20.
  • the press is subject to overload condition, which causes the pressure of the liquid 40 to increase and the plug 38 to be compressed axially.
  • the high bulk modulus of the plug body 48 is so chosen that, when the pressure exceeds a value in excess of that normally experienced during the press operation, the plug 38 is sufficientlv compressed to expose the valve port 42 to the liquid 40. When that occurs, liquid escapes through the port 42, with the results that, firstly, a part of the pressure of the liquid 40 is relieved and, secondly, when the press tool 22 is withdrawn, the position of the carrier 18, and hence of the mould 20 is lower than the initial position.
  • the mould will be properly set by the operation described above, the press tool 22 then closing on the mould 20 at the end of its compressive stroke and at bottom dead centre of the crank; in that condition, when the press tool closes on the mould, the plug 38 is only so compressed that its upper face 44 is immediately above the port 42, However, in most cases, a number of cycles of the press is required before the press is properly set.
  • the carrier 18 When proper setting has been achieved, the carrier 18 is locked in position by the clamps 24 and the screw jacks 26 and the press is operated with the carrier so locked.
  • the press When the press is to be used for a different operation or to form a different shape of workpiece, it may be necessary before the mould is used to top up the liquid 40 in the cylinder 32, so that the mould can again be automatically set for the new operation.
  • It may also be necessary to replace the existing plug 38 by another plug having different compressive properties, the replacement plug being chosen to open the valve port 42 at a safe overload pressure in excess of the proper press operation.
  • a series of plugs 38 may be provided, the axial dimensions and the bulk moduli of the bodies 48 being selected so that the different plugs open the valve port 42 at different pressure levels.
  • the plug body 48 may have a central void, illustrated in chain line in Figure 2 at 62 in order to assist the proper compression of the plug 38 under the pressure of the liquid 40: during compression, the material of the body is deformed into the void.
  • the valve port-42 is shown as having a circular cross section.
  • the cross sectional form of the port may differ from circular, if it should become necessary in order to obtain a good flow rate of liquid when the port is exposed but to minimise leakage once the proper press setting has been achieved and the port 42 continually closed by the plug; with this in view, the port 42 may have a triangular or other cross section such that the rate at which the cross sectional area of the exposed port enlarges as the plug is compressed increases as the upper surface 44 of the plug falls.
  • valve mechanisms other than that illustrated in the drawings can be employed to cause opening of a valve to release some of the liquid 40, when an overload condition arises.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Press Drives And Press Lines (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Presses And Accessory Devices Thereof (AREA)

Claims (5)

1. Presse comportant un vérin alternatif (14), un plateau (12) dont, alternativement, le vérin (14) s'approche et s'éloigne, et un porte-outil (18) supporté par le plateau (12) entre celui-ci et le vérin (14) aux fins de règlage dans la direction de la course du vérin (14), caractérisée en ce qu'elle comprend un dispositif de règlage automatique (26) installé entre le plateau (12) et le porte-outil (18) afin de déterminer la position de ce dernier par rapport au précédent et pour ajuster cette position par rapport à la course du vérin (14), le dispositif (28) comprenant un cylindre (32) contenant un fluide monté soit sur le plateau (12), soit sur le porte-outil (18), un piston (34) pouvant se déplacer dans le cylindre (32) et qui est relié an porte-outil (18) ou au plateau (12), et une valve (38-42) normalement fermée dans le cylindre (32) pour libérer une certaine quantité de fluide quand elle s'ouvre, cette valve (38-42) étant arrangée pour s'ouvrir automatiquement quand la pression du fluide dépasse une limite donnée et pour se refermer après que la pression soit retombée pratiquement à cette limite, de sorte que la position du porte outil (18) se trouve réajustée par rapport au plateau (12) et à la course du vérin (14) et des moyens (24-26) pour bloquer le porte-outil (18) dans sa nouvelle position.
2. Presse selon la revendication 1, comportant une transmission mécanique pour actionner le vérin (14), caractérisée en ce que la valve comprend un tampon rigidement compressible (38) logé dans le cylindre (32) et séparé dudit piston (34) par un certain volume de liquide (40) et un orifice (42) percé dans la paroi du cylindre (32) et qui est normalement fermé par le tampon (38) mais étant découvert de façon à libérer une certaine quantité de liquide quand le tampon (38) a été comprimé à une pression au moins égale à limite donnée.
3. Presse selon la revendication 2, caractérisée en ce que le tampon (38) comprend un corps (48) en une matière élastomérique étroitement confinée dans l'extrémité du cylindre (32) à une certaine distance du piston (34) et qui porte un capuchon d'étanchéité (52) qui s'applique de manière étanche contre le cylindre (32) et qui empêche le liquide de gagner l'orifice (42) avant que cet orifice (42) ait été découvert par suite de la déformation du tampon (38).
4. Presse selon la revendication 3, caractérisée en ce qu'elle comprend un capuchon de métal (50) interposé entre le corps (48) et le capuchon d'étranchéité (52).
5. Presse selon l'une quelconque des revendications précédentes, caractérisée en ce qu'un moule (20) pour la mise en form d'une pièce métallique, est fixé au porte-outil (18).
EP78300446A 1977-10-03 1978-10-03 Dispositif d'ajustage automatique pour une presse Expired EP0001692B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB4103477 1977-10-03
GB4103477 1977-10-03

Publications (2)

Publication Number Publication Date
EP0001692A1 EP0001692A1 (fr) 1979-05-02
EP0001692B1 true EP0001692B1 (fr) 1981-02-11

Family

ID=10417809

Family Applications (1)

Application Number Title Priority Date Filing Date
EP78300446A Expired EP0001692B1 (fr) 1977-10-03 1978-10-03 Dispositif d'ajustage automatique pour une presse

Country Status (3)

Country Link
US (1) US4235576A (fr)
EP (1) EP0001692B1 (fr)
DE (1) DE2860479D1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4364720A (en) * 1980-12-22 1982-12-21 Ryder International Corporation Molding machine and system for accomodating a plurality of such machines
FR2507509A1 (fr) * 1981-06-13 1982-12-17 Weingarten Ag Maschf Procede et dispositif pour le forgeage de pieces minces a grande surface et modeles de presses pour l'execution du procede
US5782461A (en) * 1996-12-19 1998-07-21 Lord Corporation Snubber using bulk loading
DE19809720C2 (de) * 1998-03-06 2001-02-15 Krauss Maffei Kunststofftech Tauchkantenwerkzeug für eine Spritzgießmaschine
CN104646564A (zh) * 2014-06-21 2015-05-27 柳州聚龙科技有限公司 冲压模具安全保护装置
CN106001221B (zh) * 2016-07-28 2018-03-09 无锡普瑞腾传动机械有限公司 一种齿轮加工用压痕装置

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7316227U (de) * 1975-06-19 Schenk H Hydraulisches Schnittschlagdämpfelement für Pressen
DE563922C (de) * 1931-12-25 1932-11-11 Edgar Haverbeck UEberdrucksicherung fuer Zieh-, Schnitt- und Praegepressen
GB748469A (en) * 1952-11-12 1956-05-02 Applic Mach Motrices An improved hydraulic shock absorber
DE1228512B (de) * 1961-02-21 1966-11-10 Beteiligungs & Patentverw Gmbh Hydraulische UEberlastungssicherung
GB1169192A (en) * 1966-05-17 1969-10-29 Samuel Griffiths Willenhall Lt Improvements in or relating to Power Presses and like Machines
US3571855A (en) * 1968-07-03 1971-03-23 Stubbe Maschinenfabrik Gmbh Device for stroke limitation on hydraulically displaced mold carrier units on injection molds
US3712774A (en) * 1970-10-14 1973-01-23 Improved Machinery Inc Molding machine having yieldably restrained clamping force applying element
DE2242067C3 (de) * 1972-08-26 1981-11-19 Fried. Krupp Gmbh, 4300 Essen Längenverstellbarer Pleuel für eine Presse mit hydraulischer Überlastsicherung
DE2559282A1 (de) * 1975-12-31 1977-07-14 Paul Chrubasik Presse

Also Published As

Publication number Publication date
DE2860479D1 (en) 1981-03-26
US4235576A (en) 1980-11-25
EP0001692A1 (fr) 1979-05-02

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